Additives for low-sulphur mineral oil distillates containing an ester of an alkoxylated polyol and a polar nitrogenous paraffin dispersant

ABSTRACT

An additive for low-sulfur mineral oil distillates having improved cold flowability and paraffin dispersancy, comprising at least one ester of an alkoxylated polyol and at least one polar nitrogen-containing paraffin dispersant.

Additives for low-sulfur mineral oil distillates, comprising an ester ofan alkoxylated polyol and a polar nitrogen-containing paraffindispersant

The invention relates to additives for low-sulfur mineral oildistillates having improved cold flowability and paraffin dispersancy,comprising an ester of an alkoxylated polyol and a polarnitrogen-containing paraffin dispersant, to additized fuel oils and tothe use of the additive.

In view of the decreasing crude oil reserves coupled with steadilyrising energy demand, ever more problematic crude oils are beingextracted and processed. In addition, the demands on the fuel oils, suchas diesel and heating oil, produced therefrom are becoming ever morestringent, not least as a result of legislative requirements. Examplesthereof are the reduction in the sulfur content, the limitation of thefinal boiling point and also of the aromatics content of middledistillates, which force the refineries into constant adaptation of theprocessing technology. In middle distillates, this leads in many casesto an increased proportion of paraffins, especially in the chain lengthrange of from C₁₈ to C₂₄, which in turn has a negative influence on thecold flow properties of these fuel oils.

Crude oils and middle distillates, such as gas oil, diesel oil orheating oil, obtained by distillation of crude oils contain, dependingon the origin of the crude oils, different amounts of n-paraffins whichcrystallize out as platelet-shaped crystals when the temperature isreduced and sometimes agglomerate with the inclusion of oil. Thiscrystallization and agglomeration causes a deterioration in the flowproperties of these oils or distillates, which may result in disruption,for example, in the course of extraction, transport, storage and/or useof the mineral oils and mineral oil distillates. When mineral oils aretransported through pipelines, the crystallization phenomenon can,especially in winter, lead to deposits on the pipe walls, and inindividual cases, for example in the event of stoppage of a pipeline,even to its complete blockage. When storing and further processing themineral oils, it may be necessary in winter to store the mineral oils inheated tanks. In the case of mineral oil distillates, the consequence ofcrystallization may be blockage of the filters in diesel engines andboilers, which prevents reliable metering of the fuels and in some casesresults in complete interruption of the fuel or heating medium feed.

In addition to the classical methods of eliminating the crystallizedparaffins (thermal, mechanical or using solvents), which merely involvethe removal of the precipitates which have already formed, chemicaladditives (known as flow improvers or paraffin inhibitors) have beendeveloped in recent years. By interacting physically with theprecipitating paraffin crystals, they bring about modification of theirshape, size and adhesion properties. The additives function asadditional crystal seeds and some of them crystallize out with theparaffins, resulting in a larger number of smaller paraffin crystalshaving modified crystal shape. The modified paraffin crystals have alower tendency to agglomerate, so that the oils admixed with theseadditives can still be pumped and processed at temperatures which areoften more than 20° C. lower than in the case of nonadditized oils.

Typical flow improvers for crude oils and middle distillates are co- andterpolymers of ethylene with carboxylic esters of vinyl alcohol.

A further task of flow improver additives is the dispersion of theparaffin crystals, i.e. the retardation or prevention of sedimentationof the paraffin crystals and therefore the formation of a paraffin-richlayer at the bottom of storage vessels.

The prior art also discloses certain poly(oxyalkylene) compounds andalso alkylphenol resins which are added as additives to middledistillates.

EP-A-0 061 895 discloses cold flow improvers for mineral oil distillateswhich comprise esters, ethers or mixtures thereof. The esters/etherscontain two linear saturated C₁₀- to C₃₀-alkyl groups and apolyoxyalkylene group having from 200 to 5000 g/mol.

EP-0 973 848 and EP-0 973 850 disclose mixtures or esters of alkoxylatedalcohols having more than 10 carbon atoms and fatty acids having 10-40carbon atoms in combination with ethylene copolymers as flow improvers.

EP-A-0 935 645 discloses alkylphenol-aldehyde resins as alubricity-improving additive in low-sulfur middle distillates.

EP-A-0857776 and EP-A-1 088 045 disclose processes for improving theflowability of paraffinic mineral oils and mineral oil distillates byadding ethylene copolymers and alkylphenol-aldehyde resins, and alsooptionally further, nitrogen-containing paraffin dispersants.

The above-described flow-improving and/or paraffin-dispersing action ofthe existing paraffin dispersants is not always adequate, so thatsometimes large paraffin crystals form when the oils are cooled and leadto filter blockages and, as a consequence of their relatively highdensity, sediment in the course of time and thus lead to the formationof a paraffin-rich layer at the bottom of the storage vessels. Problemsoccur in particular in the additization of paraffin-rich and narrow-cutdistillation cuts having boiling ranges from 20-90% by volume of lessthan 120° C., in particular less than 100° C. The situation isparticularly problematic in the case of low-sulfur winter qualitieshaving cloud points below −5° C.; the addition of existing additiveshere often does not lead to adequate paraffin dispersancy.

It is therefore an object of the invention to improve the flowability,and in particular the paraffin dispersancy, in the case of mineral oilsand mineral oil distillates, by the addition of suitable additives.

It has been found that, surprisingly, an additive which comprises, inaddition to polar nitrogen-containing paraffin dispersants, also certainesters of alkoxylated polyols constitutes a particularly good cold flowimprover for low-sulfur fuel oils.

The invention therefore provides additives for middle distillates havinga maximum sulfur content of 0.05% by weight, comprising at least onefatty ester of alkoxylated polyols having at least 3 OH groups (A) andat least one polar nitrogen-containing paraffin dispersant (D).

The invention further provides middle distillates having a maximumsulfur content of 0.05% by weight, which comprise an additive whichcomprises at least one fatty ester of alkoxylated polyols having atleast 3 OH groups (A) and at least one polar nitrogen-containingparaffin dispersant (D).

The invention further provides the use of an additive comprising atleast one fatty ester of alkoxylated polyols having at least 3 OH groups(A) and at least one polar nitrogen-containing paraffin dispersant (D),for improving the cold flow properties and paraffin dispersancy ofmiddle distillates having a maximum sulfur content of 0.05% by weight.

The invention further provides a process for improving the cold flowproperties of middle distillates having a maximum sulfur content of0.05% by weight, by adding to the middle distillates an additivecomprising at least one fatty ester of alkoxylated polyols having atleast 3 OH groups (A) and at least one polar nitrogen-containingparaffin dispersant (D).

The esters (A) derive from polyols having 3 or more OH groups, inparticular from glycerol, trimethylolpropane, pentaerythritol, and alsothe oligomers obtainable therefrom by condensation and having from 2 to10 monomer units, for example polyglycerol. The polyols have generallybeen reacted with from 1 to 100 mol of alkylene oxide, preferably from 3to 70 mol, in particular from 5 to 50 mol, of alkylene oxide, per moleof polyol. Preferred alkylene oxides are ethylene oxide, propylene oxideand butylene oxide. The alkoxylation is effected by known processes.

The fatty acids which are suitable for the esterification of thealkoxylated polyols preferably have from 8 to 50, in particular from 12to 30, especially from 16 to 26, carbon atoms. Suitable fatty acids are,for example, lauric acid, tridecanoic acid, myristic acid, pentadecanoicacid, palmitic acid, magaric acid, stearic acid, isostearic acid,arachic acid and behenic acid, oleic acid and erucic acid, palmitoleicacid, myristoleic acid, ricinoleic acid, and also fatty acid mixturesobtained from natural fats and oils. Preferred fatty acid mixturescontain more than 50% of fatty acids having at least 20 carbon atoms.Preferably, less than 50% of the fatty acids used for esterificationcontain double bonds, in particular less than 10%; they are especiallyvery substantially saturated. Very substantially saturated means here aniodine number of the fatty acids used of up to 5 g of I per 100 g offatty acid. The esterification may also be effected starting fromreactive derivatives of the acids such as esters with lower alcohols(for example methyl or ethyl esters) or anhydrides.

To esterify the alkoxylated polyols, mixtures of the above fatty acidswith fat-soluble, polybasic carboxylic acids may also be used. Examplesof suitable polybasic carboxylic acids are dimer fatty acids,alkenylsuccinic acids and aromatic polycarboxylic acids, and also theirderivatives such as anhydrides and C₁- to C₅-esters. Preference is givento alkenylsuccinic acid and its derivatives with alkyl radicals havingfrom 8 to 200, in particular from 10 to 50, carbon atoms. Examples aredodecenyl-, octadecenyl- and poly(isobutenyl)succinic anhydride.Preference is given to using the polybasic carboxylic acids in minoramounts of up to 30 mol %, preferably from 1 to 20 mol %, in particularfrom 2 to 10 mol %.

Esters and fatty acids are used for the esterification, based on thecontent of hydroxyl groups on the one hand and carboxyl groups on theother hand, in a ratio of from 1.5:1 to 1:1.5, preferably from 1.1:1 to1:1.1, in particular equimolar. The paraffin-dispersing action isparticularly marked when operation is effected with an acid excess of upto 20 mol %, especially up to 10 mol %, in particular up to 5 mol %.

The esterification is carried out by customary processes. It has beenfound to be particularly useful to react polyol alkoxylate with fattyacid, optionally in the presence of catalysts, for examplepara-toluenesulfonic acid, C₂- to C₅₀-alkylbenzenesulfonic acids,methanesulfonic acid or acidic ion exchangers. The water of reaction maybe removed distillatively by direct condensation or preferably by meansof azeotropic distillation in the presence of organic solvents, inparticular aromatic solvents, such as toluene, xylene or else relativelyhigh-boiling mixtures such as ®Shellsol A, Shellsol B, Shellsol AB orSolvent Naphtha. The esterification is preferably effected tocompletion, i.e. from 1.0 to 1.5 mol of fatty acid are used for theesterification per mole of hydroxyl groups. The acid number of the esteris generally below 15 mg KOH/g, preferably below 10 mg KOH/g, especiallybelow 5 mg KOH/g.

The polar nitrogen-containing paraffin dispersants (D) present in theadditive according to the invention are low molecular weight orpolymeric, oil-soluble nitrogen compounds, for example amine salts,imides and/or amides, which are obtained by reacting aliphatic oraromatic amines, preferably long-chain aliphatic amines, with aliphaticor aromatic mono-, di-, tri- or tetracarboxylic acids or theiranhydrides. Particularly preferred paraffin dispersants comprisereaction products of secondary fatty amines having from 8 to 36 carbonatoms, in particular dicoconut fatty amine, ditallow fatty amine anddistearylamine. Other paraffin dispersants are copolymers of maleicanhydride and α,β-unsaturated compounds which may optionally be reactedwith primary monoalkylamines and/or aliphatic alcohols, the reactionproducts of alkenyl-spiro-bislactones with amines and reaction productsof terpolymers based on α,β-unsaturated dicarboxylic anhydrides,α,β-unsaturated compounds and polyoxyalkylene ethers of lowerunsaturated alcohols. Some suitable paraffin dispersants (D) are listedhereinbelow.

Some of the paraffin dispersants (D) specified below are prepared byreacting compounds which contain an acyl group with an amine. This amineis a compound of the formula NR⁶R⁷R⁸ where R⁶, R⁷ and R⁸ may be the sameor different, and at least one of these groups is C₈- to C₃₆-alkyl,C₆-C₃₆-cycloalkyl, C₈-C₃₆-alkenyl, in particular C₁₂-C₂₄-alkyl, C₁₂- toC₂₄-alkenyl or cyclohexyl, and the remaining groups are either hydrogen,C₁- to C₃₆-alkyl, C₂-C₃₆-alkenyl, cyclohexyl, or a group of theformulae-(A-O)_(x)-E or —(CH₂)n-NYZ, where A is an ethylene or propylenegroup, x is a number from 1 to 50, E =H, C₁-C₃₀-alkyl, C₅-C₁₂-cycloalkylor C₆-C₃₀-aryl, and n is 2, 3 or 4, and Y and Z are each independentlyH, C₁-C₃₀-alkyl or -(A-O)_(x). An acyl group here is a functional groupof the following formula:>C=O

1. Reaction products of alkenyl-spiro-bislactones of the formula

where R is in each case C₈-C₂₀₀-alkenyl with amines of the formulaNR⁶R⁷R⁸. Suitable reaction products are detailed in EP-A-0 413 279.Depending on the reaction conditions, the reaction of compounds of theformula with amine results in amides or amide-ammonium salts.

2. Amides or ammonium salts of aminoalkylene polycarboxylic acids withsecondary amines of the formula

in which

-   -   R¹⁰ is a straight-chain or branched alkylene radical having from        2 to 6 carbon atoms or the radical of the formula        in which R⁶ and R⁷ are in particular alkyl radicals having from        10 to 30, preferably from 14 to 24, carbon atoms, and the amide        structures may also partly or completely be in the form of the        ammonium salt structure of the formula

The amides or amide-ammonium salts or ammonium salts, for example ofnitrilotriacetic acid, of ethylenediaminetetraacetic acid or ofpropylene-1,2-diaminetetraacetic acid are obtained by reacting the acidswith from 0.5 to 1.5 mol of amine, preferably from 0.8 to 1.2 mol ofamine, per carboxyl group. The reaction temperatures are from about 80to 200° C., and to prepare the amides, the water of reaction formed isremoved continuously. However, the reaction does not have to be carriedout completely to the amide but rather from 0 to 100 mol % of the amineused may be present in the form of the ammonium salt. Under similarconditions, the compounds mentioned under B1) may also be prepared.

Useful amines of the formula

are in particular dialkylamines in which R⁶,R⁷ are each a saturatedalkyl radical having from 10 to 30 carbon atoms, preferably from 14 to24 carbon atoms. Specific mention may be made of dioleylamine,dipalmitamine, dicoconut fatty amine and dibehenylamine, and preferablyditallow fatty amine.

3. Quaternary ammonium salts of the formula⁺NR⁶R⁷R⁸R¹¹X⁻where R⁶, R⁷ and R⁸ are each as defined above and R¹¹ is C₁-C₃₀-alkyl,preferably C₁-C₂₂-alkyl, C₁-C₃₀-alkenyl, preferably C₁-C₂₂-alkenyl,benzyl or a radical of the formula —(CH₂—CH₂—O)_(n)-R¹² where R¹² ishydrogen or a fatty acid radical of the formula C(O)—R¹³ whereR¹³═C₆-C₄₀-alkenyl, n is a number from 1 to 30 and X is halogen,preferably chlorine, or a methosulfate.

Examples of such quaternary ammonium salts include:dihexadecyldimethylammonium chloride, distearyidimethyl-ammoniumchloride, quaternization products of esters of di- and triethanolaminewith long-chain fatty acids (lauric acid, myristic acid, palmitic acid,stearic acid, behenic acid, oleic acid and fatty acid mixtures such ascoconut fatty acid, tallow fatty acid, hydrogenated tallow fatty acid,tall oil fatty acid), such as N-methyl-triethanolammonium distearylester chloride, N-methyltriethanolammonium distearyl ester methosulfate,N,N-dimethyidiethanolammonium distearyl ester chloride,N-methyltriethanolammonium dioleyl ester chloride,N-methyltriethanolammonium trilauryl ester methosulfate,N-methyltriethanolammonium tristearyl ester methosulfate and mixturesthereof.

4. Compounds of the formula

in which

-   -   R¹⁴ is CONR⁶R⁷ or CO₂ ⁻⁺H₂NR⁶R⁷,    -   R¹⁵ and R¹⁶ are each H, CONR¹⁷ ₂, CO₂R¹⁷ or OCOR¹⁷, —OR¹⁷, —R¹⁷        or —NCOR¹⁷, and    -   R¹⁷ is alkyl, alkoxyalkyl or polyalkoxyalkyl, and has at least        10 carbon atoms.

Preferred carboxylic acids or acid derivatives are phthalic acid(anhydride), trimellitic, pyromellitic acid (dianhydride), isophthalicacid, terephthalic acid, cyclohexanedicarboxylic acid (anhydride),maleic acid (anhydride), alkenylsuccinic acid (anhydride). Theformulation (anhydride) means that the anhydrides of the acids mentionedare also preferred acid derivatives.

When the compounds of the above formula are amides or amine salts, theyare preferably obtained from a secondary amine which contains ahydrogen- and carbon-containing group having at least 10 carbon atoms.

It is preferred that R¹⁷ contains from 10 to 30, in particular from 10to 22, for example from 14 to 20, carbon atoms and is preferablystraight-chain or branched at the 1- or 2-position. The other hydrogen-and carbon-containing group may be shorter, for example contain lessthan 6 carbon atoms, or may, if desired, have at least 10 carbon atoms.Suitable alkyl groups include methyl, ethyl, propyl, hexyl, decyl,dodecyl, tetradecyl, eicosyl and docosyl (behenyl).

Additionally suitable are polymers which contain at least one amide,imide or ammonium group bonded directly to the framework of the polymer,in which case the amide, imide or ammonium group bears at least onealkyl group of at least 8 carbon atoms on the nitrogen atom. Suchpolymers may be prepared in various ways. One way is to use a polymerwhich contains a plurality of carboxylic acid or anhydride groups, andto react this polymer with an amine of the formula NHR⁶R⁷, in order toobtain the desired polymer.

Suitable polymers for this purpose are generally copolymers ofunsaturated esters such as C₁-C₄₀-alkyl (meth)acrylates,di(C₁-C₄₀-alkyl) fumarates, C₁-C₄₀-alkyl vinyl ethers, C₁-C₄₀-alkylvinyl esters or C₂-C₄₀-olefins (linear, branched, aromatic) withunsaturated carboxylic acids or their reactive derivatives, for examplecarboxylic anhydrides (acrylic acid, methacrylic acid, maleic acid,fumaric acid, haconic acid, tetrahydrophthalic acid, citraconic acid,preferably maleic anhydride).

Carboxylic acids are reacted preferably with from 0.1 to 1.5 mol, inparticular from 0.5 to 1.2 mol, of amine per acid group, carboxylicanhydrides preferably with from 0.1 to 2.5 mol, in particular from 0.5to 2.2 mol, of amine per acid anhydride group, forming, depending on thereaction conditions, amides, ammonium salts, amide-ammonium salts orimides. This results in copolymers which contain the unsaturatedcarboxylic anhydrides, or, in the case of the reaction with a secondaryamine, as a consequence of the reaction with the anhydride group, halfamide and half amine salts. By heating, water can be eliminated to formthe diamide.

Particularly suitable examples of amide group-containing polymers forthe use according to the invention are:

5. Copolymers (a) of a dialkyl fumarate, maleate, citraconate oritaconate with maleic anhydride, or (b) of vinyl esters, e.g. vinylacetate or vinyl stearate, with maleic anhydride, or (c) of a dialkylfumarate, maleate, citraconate or itaconate with maleic anhydride andvinyl acetate.

Particularly suitable examples of these polymers are copolymers ofdidodecyl fumarate, vinyl acetate and maleic anhydride; ditetradecylfumarate, vinyl acetate and maleic anhydride; dihexadecyl fumarate,vinyl acetate and maleic anhydride; or the corresponding copolymers inwhich the itaconate is used instead of the fumarate.

In the abovementioned examples of suitable polymers, the desired amideis obtained by reacting the polymer which contains anhydride groups witha secondary amine of the formula HNR⁶R⁷ (optionally also with an alcoholwhen an esteramide is formed). When polymers which contain an anhydridegroup are reacted, the resulting amino group will be ammonium salts andamides. Such polymers may be used with the proviso that they contain atleast two amide groups.

It is essential that the polymer which contains at least two amidegroups contains at least one alkyl group having at least 10 carbonatoms. This long-chain group which may be a straight-chain or branchedalkyl group may be bonded via the nitrogen atom of the amide group.

The amines suitable for this purpose may be reproduced by the formulaR⁶R⁷NH and the polyamines by R⁶NH[R¹⁹NH]_(x)R⁷ where R¹⁹ is a bivalenthydrocarbon group, preferably an alkylene or hydrocarbon-substitutedalkylene group, and x is an integer, preferably in the range from 1 to30. Preferably, one of the two or both R⁶ and R⁷ radicals contain atleast 10 carbon atoms, for example from 10 to 20 carbon atoms, forexample dodecyl, tetradecyl, hexadecyl or octadecyl.

Examples of suitable secondary amines are dioctylamine and those whichcontain alkyl groups having at least 10 carbon atoms, for exampledidecylamine, didodecylamine, dicocoamine (i.e. mixed C₁₂-C₁₄-amines),dioctadecylamine, hexadecyloctadecylamine, di(hydrogenated tallow)amine(approximately 4% by weight of n-C₁₄-alkyl, 30% by weight ofn-C₁₀-alkyl, 60% by weight of n-C₁₈-alkyl, the remainder isunsaturated).

Examples of suitable polyamines are N-octadecylpropanediamine,N,N′-dioctadecylpropanediamine, N-tetradecylbutanediamine andN,N′-dihexadecylhexanediamine, N-cocopropylenediamine(C₁₂/C₁₄-alkylpropylenediamine), N-tallow propylenediamine(C₁₆/C₁₈-alkylpropylenediamine).

The amide-containing polymers typically have an average molecular weight(number-average) of from 1000 to 500 000, for example from 10000 to 100000.

6. Copolymers of styrene, of its derivatives or aliphatic olefins havingfrom 2 to 40 carbon atoms, preferably having from 6 to 20 carbon atoms,and olefinically unsaturated carboxylic acids or carboxylic anhydrideswhich have been reacted with amines of the formula HNR⁶R⁷. The reactionmay be carried out before or after the polymerization.

Specifically, the structural units of the copolymers derive, forexample, from maleic acid, fumaric acid, haconic acid,tetrahydrophthalic acid, citraconic acid, preferably maleic anhydride.They may be used either in the form of their homopolymers or of thecopolymers. Suitable comonomers are: styrene and alkylstyrenes,straight-chain and branched olefins having from 2 to 40 carbon atoms,and also their mixtures with each other. Examples include: styrene,α-methylstyrene, dimethylstyrene, α-ethylstyrene, diethylstyrene,i-propylstyrene, tert-butylstyrene, ethylene, propylene, n-butylene,diisobutylene, decene, dodecene, tetradecene, hexadecene, octadecene.Preference is given to styrene and isobutene, particular preferably tostyrene.

Examples of specific polymers include: polymaleic acid, a molarstyrene/maleic acid copolymer having an alternating structure,styrene/maleic acid copolymers in a ratio of 10:90 and having a randomstructure, and an alternating copolymer of maleic acid and i-butene. Themolar masses of the polymers are generally from 500 g/mol to 20 000g/mol, preferably from 700 to 2000 g/mol.

The reaction of the polymers or copolymers with the amines is effectedat temperatures of from 50 to 200° C. over the course of from 0.3 to 30hours. The amine is employed in amounts of from about one mole per moleof copolymerized dicarboxylic anhydride, i.e. from approx. 0.9 to 1.1mol/mol. The use of greater or lesser amounts is possible, but brings noadvantage. When amounts larger than one mole are used, some ammoniumsalts are obtained, since the formation of a second amide moietyrequires higher temperatures, longer residence times and separation ofwater. Where amounts smaller than one mole are employed, there isincomplete conversion to the monoamide and a correspondingly reducedaction is obtained.

Instead of the subsequent reaction of the carboxyl groups in the form ofthe dicarboxylic anhydride with amines to give the corresponding amides,it may sometimes be advantageous to prepare the monoamides of themonomers and then to directly copolymerize them in the polymerization.However, this is technically far more complicated, since the amines canadd to the double bond of the monomeric mono- and dicarboxylic acid andcopolymerization is then no longer possible.

7. Copolymers consisting of from 10 to 95 mol % of one or more alkylacrylates or alkyl methacrylates with C₁-C₂₆-alkyl chains and of from 5to 90 mol % of one or more ethylenically unsaturated dicarboxylic acidsor their anhydrides, the copolymer having been converted substantiallyto the monoamide or amide/ammonium salt of the dicarboxylic acid usingone or more primary or secondary amines.

From 10 to 95 mol %, preferably from 40 to 95 mol % and more preferablyfrom 60 to 90 mol %, of the copolymers consists of alkyl(meth)acrylates, and from 5 to 90 mol %, preferably from 5 to 60 mol %and more preferably from 10 to 40 mol %, of the copolymers consist ofthe olefinically unsaturated dicarboxylic acid derivatives. The alkylgroups of the alkyl (meth)acrylates contain of from 1 to 26, preferablyfrom 4 to 22 and more preferably from 8 to 18, carbon atoms. They arepreferably straight-chain and unbranched. However, up to 20% by weightof cyclic and/or branched fractions may also be present.

Examples of particularly preferred alkyl (meth)acrylates are n-octyl(meth)acrylate, n-decyl (meth)acrylate, n-dodecyl (meth)acrylate,n-tetradecyl (meth)acrylate, n-hexadecyl (meth)acrylate and noctadecyl(meth)acrylate and also mixtures thereof.

Examples of ethylenically unsaturated dicarboxylic acids are maleicacid, tetrahydrophthalic acid, citraconic acid and itaconic acid andtheir anhydrides, and also fumaric acid. Preference is given to maleicanhydride.

Useful amines are compounds of the formula HNR⁶R⁷.

In general, it is advantageous to use the dicarboxylic acids in the formof the anhydrides, where available, in the copolymerization, for examplemaleic anhydride, itaconic anhydride, citraconic anhydride andtetrahydrophthalic anhydride, since the anhydride is generallycopolymerized better with the (meth)acrylates. The anhydride groups ofthe copolymers may then be reacted directly with the amines.

The reaction of the polymers with the amines is effected at temperaturesof from 50 to 200° C. over the course of from 0.3 to 30 hours. The amineis employed in amounts of from about one to two mol per mole ofcopolymerized dicarboxylic anhydride, i.e. from approx. 0.9 to 2.1mol/mol. The use of greater or lesser amounts is possible, but brings noadvantage. When amounts greater than two moles are employed, free amineis present. When amounts smaller than one mole are employed, there isincomplete conversion to the monoamide and a correspondingly reducedaction is obtained.

In some cases, it may be advantageous when the amide/ammonium saltstructure is composed of two different amines. For example, a copolymerof lauryl acrylate and maleic anhydride may first be reacted with asecondary amine such as hydrogenated ditallow fatty amine to give theamide, whereupon the free carboxyl group stemming from the anhydride isneutralized with another amine, for example 2-ethylhexylamine, to givethe ammonium salt. The opposite procedure is equally conceivable:initial reaction with ethylhexylamine to give the monoamide is followedby reaction with ditallow fatty amine to give the ammonium salt.Preference is given to using at least one amine which has at least onestraight-chain, unbranched alkyl group having more than 16 carbon atoms.It is unimportant whether this amine is present in the construction ofthe amide structure or as the ammonium salt of the dicarboxylic acid.

Instead of the subsequent reaction of the carboxyl groups or of thedicarboxylic anhydride with amines to give the corresponding amides oramide/ammonium salts, it may sometimes be advantageous to prepare themonoamides or amide/ammonium salts of the monomers and then tocopolymerize them directly in the polymerization. However, this isusually far more technically complicated since the amines can add to thedouble bond of the monomeric dicarboxylic acid and copolymerization isthen no longer possible.

8. Terpolymers based on α,β-unsaturated dicarboxylic an hydrides,α,β-unsaturated compounds and polyoxyalkylene ethers of lower,unsaturated alcohols, which are characterized in that they contain 20-80mol %, preferably 40-60 mol %, of bivalent structural units of theformulae 1 and/or 3, and also optionally 2, the structural units 2stemming from unconverted anhydride radicals

where

-   -   R²² and R²³ are each independently hydrogen or methyl,    -   a, b are each zero or one and a+b equals one,    -   R²⁴ and R²⁵ are the same or different and are each the —NHR⁶,        N(R⁶)₂ and/or —OR²⁷ groups, and R²⁷ is a cation of the formula        H₂N(R⁶)₂ or H₃NR⁶,    -   19-80 mol %, preferably 39-60 mol %, of bivalent structural        units of the formula 4        where    -   R²⁸ is hydrogen or C₁-C₄-alkyl and    -   R²⁹ is C₆-C₆₀-alkyl or C₆-C₁₈-aryl and

1-30 mol %, preferably 1-20 mol %, of bivalent structural units of theformula 5

where

-   -   R³⁰ is hydrogen or methyl,    -   R³¹ is hydrogen or C₁-C₄-alkyl,    -   R³³ is C₁-C₄-alkylene,    -   m is a number from 1 to 100,    -   R³² is C₁-C₂₄-alkyl, C₅-C₂₀-cycloalkyl, C₆-C₁₈-aryl or —C(O)R³⁴        where R³⁴ is C₁-C₄₀-alkyl, C₅-C₁₀-cycloalkyl or C₆-C₁₈-aryl.

The aforementioned alkyl, cycloalkyl and aryl radicals may optionally besubstituted. Suitable substituents of the alkyl and aryl radicals are,for example, (C₁-C₆)alkyl, halogens such as fluorine, chlorine, bromineand iodine, preferably chlorine, and (C₁-C₆)alkoxy.

Alkyl here is a straight-chain or branched hydrocarbon radical. Specificexamples include: n-butyl, tert-butyl, n-hexyl, n-octyl, decyl, dodecyl,tetradecyl, hexadecyl, octadecyl, dodecenyl, tetrapropenyl,tetradecenyl, pentapropenyl, hexadecenyl, octadecenyl and eicosanyl ormixtures such as cocoalkyl, tallow fat alkyl and behenyl.

Cycloalkyl here is a cyclic aliphatic radical having 5-20 carbon atoms.Preferred cycloalkyl radicals are cyclopentyl and cyclohexyl.

Aryl here is an optionally substituted aromatic ring system having from6 to 18 carbon atoms.

The terpolymers consist of the bivalent structural units of the formulae1 and 3 and also 4 and 5 and optionally 2. In a manner known per se,they also contain only the end groups formed in the polymerization byinitiation, inhibition and chain breaking.

Specifically, the structural units of the formulae 1 to 3 derive fromα,β-unsaturated dicarboxylic anhydrides of the formulae 6 and 7

such as maleic anhydride, itaconic anhydride, citraconic anhydride,preferably maleic anhydride.

The structural units of the formula 4 derive from the a,p-unsaturatedcompounds of the formula 8.

The following α,β-unsaturated olefins are mentioned by way of example:styrene, α-methylstyrene, dimethylstyrene, α-ethylstyrene,diethylstyrene, i-propylstyrene, tert-butylstyrene, diisobutylene andα-olefins, such as decene, dodecene, tetradecene, pentadecene,hexadecene, octadecene, C₂₀-α-olefin, C₂₄-α-olefin, C₃₀-α-olefin,tripropenyl, tetrapropenyl, pentapropenyl and mixtures thereof.Preference is given to a-olefins having from 10 to 24 carbon atoms andstyrene, particular preference to a-olefins having from 12 to 20 carbonatoms.

The structural units of the formula 5 derive from polyoxyalkylene ethersof lower, unsaturated alcohols of the formula 9.

The monomers of the formula 9 are etherification products (R³²═—C(O)R³⁴)or esterification products (R³²═—C(O)R³⁴) of polyalkylene ethers(R³²═H).

The polyoxyalkylene ethers (R³²═H) can be prepared by known processes byadding α-olefin oxides, such as ethylene oxide, propylene oxide and/orbutylene oxide, to polymerizable lower, unsaturated alcohols of theformula 10

Such polymerizable lower unsaturated alcohols are, for example, allylalcohol, methallyl alcohol, butenols such as 3-buten-1-ol and1-buten-3-ol, or methylbutenols such as 2-methyl-3-buten-1-ol,2-methyl-3-buten-2-ol and 3-methyl-3-buten-1-ol. Preference is given toaddition products of ethylene oxide and/or propylene oxide to allylalcohol.

A subsequent etherification of these polyoxyalkylene ethers to givecompounds of the formula 9 where R³²═C₁-C₂₄-alkyl, cycloalkyl or aryl isaffected by processes known per se. Suitable processes are disclosed,for example, by J. March, Advanced Organic Chemistry, 2nd edition, p.357 f (1977). These etherification products of the polyoxyalkyleneethers can also be prepared by adding α-olefin oxides, preferablyethylene oxide, propylene oxide and/or butylene oxide, to alcohols ofthe formula 11R³²—OH   (11)where R³² is C₁-C₂₄-alkyl, C₅-C₂₀-cycloalkyl or C₆-C₁₈-aryl, by knownmethods, and reacting with polymerizable lower, unsaturated halides ofthe formula 12

where W is a halogen atom. The halides used are preferably the chloridesand bromides. Suitable preparative processes are mentioned, for example,in J. March, Advanced Organic Chemistry, 2nd edition, p. 357 f (1977).

The esterification of the polyoxyalkylene ethers (R³²═—C(O)—R³⁴) iseffected by reaction with customary esterifying agents such ascarboxylic acids, carbonyl halides, carboxylic anhydrides or carboxylicesters with C₁-C₄-alcohols. Preference is given to using the halides andanhydrides of C₁-C₄₀-alkyl-, C₅-C₁₀-cycloalkyl- or C₆-C₁₈-arylcarboxylicacids. The esterification is generally carried out at temperatures offrom 0 to 200° C., preferably from 10 to 100° C.

In the monomers of the formula 9, the index m indicates the degree ofalkoxylation, i.e. the number of moles of α-olefin which are added permole of the formula 20 or 21.

Suitable primary amines for preparing the terpolymers include, forexample, the following:

-   -   n-hexylamine, n-octylamine, n-tetradecylamine, n-hexadecylamine,        n-stearylamine or else N,N-dimethylaminopropylenediamine,        cyclohexylamine, dehydroabietylamine and also mixtures thereof.

Suitable secondary amines for preparing the terpolymers include, forexample: didecylamine, ditetradecylamine, distearylamine, dicoconut fatamine, ditallow fat amine and mixtures thereof.

The terpolymers have K values (measured according to Ubbelohde in 5% byweight solution in toluene at 25° C.) of from 8 to 100, preferably from8 to 50, corresponding to average molecular weights (Mw) of betweenapprox. 500 and 100 000. Suitable examples are detailed in EP 606 055.

9. Reaction products of alkanolamines and/or polyetheramines withpolymers containing dicarboxylic anhydride groups, characterized in thatthey contain 20-80 mol %, preferably 40-60 mol %, of bivalent structuralunits of the formulae 13 and 15 and optionally 14

where

-   -   R²² and R²³ are each independently hydrogen or methyl,    -   a, b are each zero or 1 and a+b equals 1,    -   R³⁷═—OH, —O—[C₁-C₃₀-alkyl], —NR⁶R⁷, —O^(s)N^(r)R⁶R⁷H₂    -   R³⁸═R³⁷ or NR⁶R³⁹    -   R³⁹═—(A-O)_(x)-E        where    -   A=ethylene or propylene group    -   x=from 1 to 50    -   E=H, C₁-C₃₀-alkyl, C₅-C₁₂-cycloalkyl or C₆-C₃₀-aryl, and 80-20        mol %, preferably 60-40 mol %, of bivalent structural units of        the formula 4.

Specifically, the structural units of the formulae 13, 14 and 15 derivefrom α,β-unsaturated dicarboxylic anhydrides of the formulae 6 and/or 7.

The structural units of the formula 4 derive from the α,β-unsaturatedolefins of the formula 8. The aforementioned alkyl, cycloalkyl and arylradicals have the same definitions as under 8.

The R37 and R38. radicals in formula 13 and the R39 radical in formula15 derive from polyetheramines or alkanolamines of the formulae 16 a)and b), amines of the formula NR6R7R8, and also optionally from alcoholshaving from 1 to 30 carbon atoms.

In these formulae,

-   -   R⁵³ is hydrogen, C₆-C₄₀-alkyl or    -   R⁵⁴ is hydrogen, C₁-C₄-alkyl,    -   R⁵⁵ is hydrogen, C₁-C₄-alkyl, C₅- to C₁₂-cycloalkyl or C₆- to        C₃₀-aryl,    -   R^(56,) R⁵⁷ are each independently hydrogen, C₁- to C₂₂-alkyl,        C₂- to C₂₂-alkenyl or Z-OH,    -   Z is C₂- to C₄-alkylene,    -   n is a number between 1 and 1000.

To derivatize the structural units of the formulae 6 and 7, preferenceis given to using mixtures of at least 50% by weight of alkylamines ofthe formula HNR R R and at most 50% by weight of polyetheramines,alkanolamines of the formulae 16 a) and b).

It is possible to prepare the polyetheramines used, for example, byreductively aminating polyglycols. The preparation of polyetheramineshaving a primary amine group also succeeds by adding polyglycols toacrylonitrile and subsequently catalytically hydrogenating. It isadditionally possible to obtain polyetheramines by reacting polyetherswith phosgene or thionyl chloride and subsequently aminating to give thepolyetheramine. The polyetheramines used according to the invention arecommercially available (for example) under the name ®Jeffamine (Texaco).Their molecular weight is up to 2000 g/mol and the ethyleneoxide/propylene oxide ratio is from 1:10 to 6:1.

A further possibility for derivatizing the structural units of theformulae 6 and 7 is, instead of the polyetheramines, to use analkanolamine of the formulae 16a) or 16b) and subsequently subject it toan oxalkylation.

Per mole of anhydride, from 0.01 to 2 mol, preferably from 0.01 to 1mol, of alkanolamine are used. The reaction temperature is between 50and 100° C. (amide formation). In the case of primary amines, theconversion is effected at temperatures above 100° C. (imide formation).

The oxalkylation is typically effected at temperatures between 70 and170° C. with catalysis by bases, such as NaOH or NaOCH₃, by injectinggaseous alkylene oxides such as ethylene oxide (EO) and/or propyleneoxide (PO). Typically, per mole of hydroxyl groups, from 1 to 500 mol,preferably from 1 to 100 mol, of alkylene oxide are added.

Examples of suitable alkanolamines include: monoethanolamine,diethanolamine, N-methylethanolamine, 3-aminopropanol, isopropanol,diglycolamine, 2-amino-2-methyl-propanol and mixtures thereof.

Examples of primary amines include the following: n-hexylamine,n-octylamine, n-tetradecylamine, n-hexadecylamine, n-stearylamine andalso N,N-dimethylaminopropylenediamine, cyclohexylamine,dehydroabietylamine and mixtures thereof.

Examples of secondary amines include: didecylamine, ditetradecylamine,dicoconut fat amine, ditallow fat amine and mixtures thereof.

Examples of alcohols include: methanol, ethanol, propanol, isopropanol,n-, sec-, tert-butanol, octanol, tetradecanol, hexadecanol, octadecanol,tallow fat alcohol, behenyl alcohol and mixtures thereof. Suitableexamples are listed in EP-A-688 796.

10. Co- and terpolymers of N-C₆-C₂₄-alkylmaleimide with C₁-C₃₀-vinylesters, vinyl ethers and/or olefins having from 1 to 30 carbon atoms,for example styrene or α-olefins. These are obtainable either byreacting a polymer containing anhydride groups with amines of theformula H2NR6 or by imidating the dicarboxylic acid and subsequentlycopolymerizing. A preferred dicarboxylic acid is maleic acid or maleicanhydride. Preference is given to polymers which are composed of from 10to 90% by weight of C₆-C₂₄-α-olefins and from 90 to 10% by weight ofN-C₆-C₂₂-alkylmaleimide.

In a preferred embodiment of the invention, to the additives and fueloils according to the invention which contains the constituents (A) and(C) may also be added ethylene copolymers (B), alkylphenol-aldehyderesins (C) and/or comb polymers. Preferred embodiments are consequentlyalso fuel oils according to the invention which comprise ethylenecopolymers (B), alkylphenol-aldehyde resins (C) and/or comb polymers,and also the use according to the invention of additives which compriseethylene copolymers (B), alkylphenol-aldehyde resins (C) and/or combpolymers, and the corresponding process.

Copolymer B) is preferably an ethylene copolymer having an ethylenecontent of from 60 to 90 mol % and a comonomer content of from 10 to 40mol %, preferably from 12 to 18 mol %. Suitable comonomers are vinylesters of aliphatic carboxylic acids having from 2 to 15 carbon atoms.

Preferred vinyl esters for copolymer B) are vinyl acetate, vinylpropionate, vinyl hexanoate, vinyl octanoate, vinyl-2-ethylhexanoate,vinyl laurate and vinyl esters of neocarboxylic acids, here inparticular of neononanoic, neodecanoic and neoundecanoic acid.Particular preference is given to an ethylene-vinyl acetate copolymer,an ethylene-vinyl propionate copolymer, an ethylene-vinyl acetate-vinyloctanoate terpolymer, an ethylene-vinyl acetate-vinyl 2-ethylhexanoateterpolymer, an ethylene-vinyl acetate-vinyl neononanoate terpolymer oran ethylene-vinyl acetate-vinyl neodecanoate terpolymer. Preferredacrylic esters are acylic esters with alcohol radicals having from 1 to20, in particular from 2 to 12 and especially from 4 to 8, carbon atoms,for example methyl acrylate, ethyl acrylate and 2-ethylhexyl acrylate.The copolymers may contain up to 5% by weight of further comonomers.Such comonomers may be, for example, vinyl esters, vinyl ethers, alkylacrylates, alkyl methacrylates having C₁- to C₂₀-alkyl radicals,isobutylene and olefins. Preferred as higher olefins are hexene,isobutylene, octene and/or diisobutylene. Further suitable comonomersare olefins such as propene, hexene, butene, isobutene, diisobutylene,4-methylpentene-1 and norbornene. Particular preference is given toethylene-vinyl acetate-diisobutylene and ethylene-vinylacetate-4-methylpentene-1 terpolymers.

The copolymers preferably have melt viscosities at 140° C. of from 20 to10 000 mPas, in particular from 30 to 5000 mPas, especially from 50 to2000 mPas.

The copolymers (B) can be prepared by the customary copolymerizationprocesses, for example suspension polymerization, solutionpolymerization, gas phase polymerization or high pressure bulkpolymerization. Preference is given to high pressure bulk polymerizationat pressures of preferably from 50 to 400 MPa, in particular from 100 to300 MPa, and temperatures of preferably from 50 to 350° C., inparticular from 100 to 250° C. The reaction of the monomers is initiatedby radical-forming initiators (radical chain starters). This substanceclass includes, for example, oxygen, hydroperoxides, peroxides and azocompounds, such as cumene hydroperoxide, t-butyl hydroperoxide,dilauroyl peroxide, dibenzoyl peroxide, bis(2-ethylhexyl) peroxidecarbonate, t-butyl perpivalate, t-butyl permaleate, t-butyl perbenzoate,dicumyl peroxide, t-butyl cumyl peroxide, di-(t-butyl) peroxide,2,2′-azobis(2-methylpropionitrile), 2,2′-azobis(2-methylbutyronitrile).The initiators are used individually or as a mixture of two or moresubstances in amounts of from 0.01 to 20% by weight, preferably from0.05 to 10% by weight, based on the monomer mixture.

The high pressure bulk polymerization is carried out in known highpressure reactors, for example autoclaves or tubular reactors, batchwiseor continuously, and tubular reactors have been found to be particularlyuseful. Solvents such as aliphatic and/or aromatic hydrocarbons orhydrocarbon mixtures, benzene or toluene may be present in the reactionmixture. Preference is given to working without solvent. In a preferredembodiment of the polymerization, the mixture of the monomers, theinitiator and, where used, the moderator are fed to a tubular reactorvia the reactor inlet and also via one or more side branches. Themonomer streams may have different compositions (EP-A-0 271 738).

Suitable co- or terpolymers include, for example:

-   -   ethylene-vinyl acetate copolymers having 10-40% by weight of        vinyl acetate and 60-90% by weight of ethylene;    -   the ethylene-vinyl acetate-hexene terpolymers disclosed by        DE-A-34 43 475;    -   the ethylene-vinyl acetate-diisobutylene terpolymers described        in EP-B-0 203 554;    -   the mixture of an ethylene-vinyl acetate-diisobutylene        terpolymer and an ethylene-vinyl acetate copolymer disclosed by        EP-B-0 254 284;    -   the mixtures of an ethylene-vinyl acetate copolymer and an        ethylene-vinyl acetate-N-vinylpyrrolidone terpolymer disclosed        in EP-B-0 405 270;

the ethylene-vinyl acetate-isobutyl vinyl ether terpolymers described inEP-B-0 463 518;

-   -   the copolymers of ethylene with vinyl alkylcarboxylates        disclosed in EP-B-0 491 225;    -   the ethylene-vinyl acetate-vinyl neononanoate or -vinyl        neodecanoate terpolymers which are disclosed by EP-B-0 493 769        and, apart from ethylene, contain 10-35% by weight of vinyl        acetate and 1-25% by weight of the particular neo- compound;    -   the terpolymers, described in DE-A-196 20 118, of ethylene, the        vinyl ester of one or more aliphatic C₂- to C₂₀-monocarboxylic        acids and 4-methyl-pentene-1;    -   the terpolymers, disclosed in DE-A-196 20 119, of ethylene, the        vinyl ester of one or more aliphatic C₂- to C₂₀-monocarboxylic        acids and bicyclo[2.2.1 ]hept-2-ene.

The ethylene copolymers may be used individually or as a mixture withdifferent types of polymer.

The alkylphenol-aldehyde resins (C) are known in principle and aredescribed, for example, in Römpp Chemie Lexikon, 9th edition, ThiemeVerlag 1988-92, volume 4, p. 3351 ff. The alkyl radicals of the o- orp-alkyl-phenol have 1-50, preferably 4-20, in particular 6-12, carbonatoms; they are preferably n-, iso- and tert-butyl, n- and isopentyl, n-and isohexyl, n- and isooctyl, n- and isononyl, n- and isodecyl, n- andisododecyl, and also tetrapropenyl, pentapropenyl and polyisobutenyl.The alkylphenol-aldehyde resin may also contain up to 50 mol % of phenolunits. For the alkylphenol-aldehyde resin, identical or differentalkylphenols may be used. The aliphatic aldehyde in thealkylphenol-aldehyde resin has 1-10, preferably 1-4, carbon atoms, andmay bear further functional groups such as aldehyde or carboxyl groups.It is preferably formaldehyde. The molecular weight of thealkylphenol-aldehyde resins is 400-10000 g/mol, preferably 400-5000g/mol. A prerequisite is that the resins are oil-soluble.

The alkylphenol-aldehyde resins are prepared in a manner known per se bybasic catalysis to form condensation products of the resol type or byacidic catalysis to form condensation products of the novolak type.

The condensates obtained in both ways are suitable for the compositionsaccording to the invention. Preference is given to condensing in thepresence of acidic catalysts.

To prepare the alkylphenol-aldehyde resins, a bifunctional o- orp-alkyl-phenol having from 1 to 50 carbon atoms, preferably from 4 to20, in particular from 6 to 12, carbon atoms, per alkyl group, ormixtures thereof, and an aliphatic aldehyde having from 1 to 10 carbonatoms are reacted together, using 0.5-2 mol, preferably 0.7-1.3 mol andin particular equimolar amounts, of aldehyde per mole of alkylphenolcompound.

Suitable alkylphenols are in particular C₄- to C₅₀-alkylphenols, forexample o- or p-cresol, n-, sec- and tert-butylphenol, n- andi-pentylphenol, n- and isohexylphenol, n- and isooctylphenol, n- andisononylphenol, n- and isodecylphenol, n- and isododecylphenol,tetradecylphenol, hexadecyl-phenol, octadecylphenol, eicosylphenol,tripropenylphenol, tetrapropenyl-phenol and poly(isobutenyl)phenol.

The alkylphenols are preferably para-substituted. Preferably at most 7mol %, in particular at most 3 mol %, of them are substituted by morethan one alkyl group.

Particularly suitable aldehydes are formaldehyde, acetaldehylde,butyraldehyde and glutaraldehyde; preference is given to formaldehyde.

The formaldehyde may be used in the form of paraformaldehyde or in theform of a preferably 20-40% by weight aqueous formalin solution.Appropriate amounts of trioxane may also be used.

Alkylphenol and aldehyde are typically reacted in the presence ofalkaline catalysts, for example alkali metal hydroxides or alkylamines,or of acidic catalysts, for example inorganic or organic acids such ashydrochloric acid, sulfuric acid, phosphoric acid, sulfonic acid,sulfamido acids or haloacetic acids, and in the presence of an organicsolvent which forms an azeotrope with water, for example toluene,xylene, higher aromatics or mixtures thereof. The reaction mixture isheated to a temperature of from 90 to 200° C., preferably 100-160° C.,and the water of reaction formed during the reaction is removed byazeotropic distillation. Solvents which do not release any protons underthe conditions of the condensation may remain in the products after thecondensation reaction. The resins may be used directly or afterneutralization of the catalyst, optionally after further dilution of thesolution with aliphatic and/or aromatic hydrocarbons or hydrocarbonmixtures, for example benzine fractions, kerosene, decane, pentadecane,toluene, xylene, ethylbenzene or solvents such as ®Solvent Naphtha,®Shellsol AB, ®Solvesso 150, ®Solvesso 200, ®Exxsol, ®ISOPAR and®Shellsol D types.

The alkylphenol resins may subsequently optionally be alkoxylated byreacting with from 1 to 10 mol, especially from 1 to 5 mol, of alkyleneoxide such as ethylene oxide, propylene oxide or butylene oxide, perphenolic OH group.

Finally, in a further embodiment of the invention, the additives andmiddle distillates according to the invention may contain comb polymers.This refers to polymers in which hydrocarbon radicals having at least 8,in particular at least 10, carbon atoms are bonded to a polymerbackbone. These are preferably homopolymers whose alkyl side chains haveat least 8 and in particular at least 10 carbon atoms. In copolymers, atleast 20%, preferably at least 30%, of the monomers have side chains(cf. Comb-like Polymers-Structure and Properties; N. A. Platé and V. P.Shibaev, J. Polym. Sci. Macromolecular Revs. 1974, 8, 117 ff). Examplesof suitable comb polymers are, for example, fumarate/vinyl acetatecopolymers (cf. EP 0 153 176 A1), copolymers of a C₆-C₂₄-α-olefin and anN-C₆-C₂₂-alkylmaleimide (cf. EP 0 320 766), and also esterifiedolefin/maleic anhydride copolymers, polymers and copolymers of a-olefinsand esterified copolymers of styrene and maleic anhydride.

Comb polymers can be described, for example, by the formula

In this structure,

-   -   A is R′, COOR′, OCOR′, R″—COOR′ or OR′;    -   D is H, CH₃, A or R;    -   E is H or A;    -   G is H, R″, R″—COOR′, an aryl radical or a heterocyclic radical;    -   M is H, COOR″, OCOR″, OR″or COOH;    -   N is H, R″, COOR″, OCOR, COOH or an aryl radical;    -   R′ is a hydrocarbon chain having 8-150 carbon atoms;    -   R″ is a hydrocarbon chain having from 1 to 10 carbon atoms;    -   m is a number between 0.4 and 1.0; and    -   n is a number between 0 and 0.6.

The mixing ratio (in parts by weight) of the additives according to theinvention with paraffin dispersants, resins and comb polymers is in eachcase from 1:10 to 20:1, preferably from 1:1 to 10:1.

The additive components according to the invention may be added tomineral oils or mineral oil distillates separately or in a mixture. In apreferred embodiment, the individual additive constituents or else thecorresponding mixture are dissolved or dispersed in an organic solventor dispersant before the addition to the middle distillates. Thesolution or suspension generally contains 5-90% by weight, preferably5-75% by weight, of the additive or additive mixture.

Suitable solvents or dispersants in this context are aliphatic and/oraromatic hydrocarbons or hydrocarbon mixtures, for example benzinefractions, kerosene, decane, pentadecane, toluene, xylene, ethylbenzeneor commercial solvent mixtures such as Solvent Naphtha, ®Shellsol AB,®Solvesso 150, ®Solvesso 200, ®Exxsol, ®ISOPAR and ®Shellsol D types.Polar solubilizers such as 2-ethylhexanol, decanol, isodecanol orisotridecanol may optionally also be added.

Mineral oils or mineral oil distillates having cold properties improvedby the additives according to the invention contain from 0.001 to 2% byweight, preferably from 0.005 to 0.5% by weight, of the additives, basedon the mineral oil or mineral oil distillate.

The additives according to the invention are especially suitable forimproving the cold flow properties of animal, vegetable or mineral oils.At the same time, they improve the dispersancy of the precipitatedparaffins below the cloud point. They are particularly suitable for usein middle distillates. Middle distillates refer in particular to thosemineral oils which are obtained by distilling crude oil and boil in therange from 120 to 450° C., for example kerosene, jet fuel, diesel andheating oil. Preference is given to using the additives according to theinvention in low-sulfur middle distillates which contain 350 ppm ofsulfur and less, more preferably less than 200 ppm of sulfur and inparticular less than 50 ppm of sulfur. The additives according to theinvention are also preferably used in those middle distillates whichhave 95% distillation points below 365° C., especially 350° C. and inspecial cases below 330® C., and contain high contents of paraffinshaving from 18 to 24 carbon atoms but only small fractions of paraffinshaving chain lengths of 24 and more carbon atoms. They may also be usedas components in lubricant oils.

The mineral oils and mineral oil distillates may also comprise furthercustomary additives, for example dewaxing auxiliaries, corrosioninhibitors, antioxidants, lubricity additives, sludge inhibitors, cetanenumber improvers, detergency additives, dehazers, conductivity improversor dyes.

EXAMPLES

The following esters A) were used as a 50% solution in aromatic solvent(EO stands for ethylene oxide; PO stands for propylene oxide): TABLE 1Characterization of the esters used (constituent A) Main constituents ofthe fatty acids Acid number OH number Additive Polyol Alkoxylation C₁₈C₂₀ C₂₂ [mg KOH/g] [mg KOH/g] A1 Glycerol 22 mol EO 2 7 88 7 13 A2Glycerol 22 mol EO 95% 5 4 A3 Glycerol 22 mol EO 37 10 48 1 2 A4Glycerol 16 mol EO 37 10 48 7 9 A5 Glycerol 16 mol EO 2 7 88 5 7 A6Glycerol 24 mol EO 37 10 48 8 11 A7 Glycerol 10 mol EO 2 7 88 7 9 A8Glycerol 30 mol EO 2 7 88 2 4 A9 Glycerol 40 mol EO 2 7 88 12 10 A10Glycerol 20 mol EO 36 36 24 13 13 A11 Glycerol 20 mol EO 2 7 88 0.5 11A12 Glycerol 15 mol EO 2 7 88 5 7 A13(C) Ethylene 13 mol EO 37 10 48 0.94 glycol A14(C) Glycerol — 2 7 88 0.2 4 A15 Glycerol ethoxylate (20 molEO) esterified with mixture of behenic acid (2% C₁₈,7% C₂₀, 88% C₂₂) and10 mol % of poly(isobutenylsuccinic anhydride) (MW 1000 g/mol)Characterization of the Ethylene Copolymers Used as Flow Improvers(Constituent B)

The viscosity was measured to ISO 3219/B using a rotational viscometer(Haake RV20) having a cone-and-plate measuring system at 140° C.Additive No. Comonomers (apart from ethylene) V₁₄₀ B 1) 32% by wt. ofvinyl acetate 125 mPas B 2) 31% by wt. of vinyl acetate + 110 mPas 8% bywt. of vinyl decanoate B 3) Mixture of copolymers B1) and B2) in a ratioof 1:5

The additives are used as 50% solutions in Solvent Naphtha or keroseneto improve the ease of handling.

Characterization of the alkylphenol-aldehyde Resins Used (ConstituentC))

C 1) nonylphenol-formaldehyde resin

C 2) dodecylphenol-formaldehyde resin

C 3) C_(20/24)-alkylphenol-formaldehyde resin

Characterization of the Paraffin Dispersants Used (Constituent D))

D 1) reaction product of a dodecenyl-spiro-bislactone with a mixture ofprimary and secondary tallow fat amine

D 2) reaction product of terpolymer of C₁₄/C₁₆-α-olefin, maleicanhydride and ally polyglycol with 2 equivalents of ditallow fat amine.

Characterization of the Test Oils:

The boiling parameters were determined to ASTM D-86, the CFPP value toEN 116 and the cloud points to ISO 3015. TABLE 2 Parameters of the testoils Test Test oil 1 Test oil 2 Test oil 3 oil 4 Initial boiling point[° C.] 169 200 174 241 20% [° C.] 211 251 209 256 90% [° C.] 327 342 327321 95% [° C.] 344 354 345 341 Cloud point [° C.] −9.0 −4.2 −6.7 −8.2CFPP [° C.] −10 −6 −8 −10 Sulfur content 33 ppm 35 ppm 210 ppm 45 ppmEffectiveness of the Additives

In Table 4, the superior effectiveness compared to the prior art of theadditives according to the invention together with ethylene copolymersfor mineral oils and mineral oil distillates is described with referenceto the CFPP test (Cold Filter Plugging Test to EN 116).

The paraffin dispersancy in middle distillates was determined in shortsedimentation test as follows:

150 ml of the middle distillates specified in the table, admixed withadditive components, in 200 ml measuring cylinders were cooled in a coldcabinet at −2° C./hour to −13° C. and stored at this temperature for 16hours. Subsequently, volume and appearance, both of the sedimentedparaffin phase and the supernatant oil phase, were determined andassessed. A small amount of sediment with a simultaneously homogeneouscloudy oil phase or a large volume of sediment with a clear oil phaseshow good paraffin dispersancy. In addition, the lower 20% by vol. wasisolated and the cloud point determined to ISO 3015. Only a smalldeviation of the cloud point of the lower phase (CP_(CC)) from the blankvalue of the oil shows good paraffin dispersancy. TABLE 3 CFPPeffectiveness in test oil 1 The CFPP effectiveness of the esters Aaccording to the invention was measured in combination with the sameamounts of C and D in test oil 1 as follows: B3 in ppm A C D 50 75 100Example 1 50 ppm A1 50 ppm C1 50 ppm D2 −29 −31 −30 Example 2 50 ppm A1150 ppm C2 50 ppm D1 −27 −30 −30 Example 3 50 ppm A7 50 ppm C1 50 ppm D2−17 −28 −29 Example 4 50 ppm A12 50 ppm C1 50 ppm D2 −19 −31 −29 Example5 50 ppm A8 50 ppm C1 50 ppm D2 −21 −29 −29 Example 6 50 ppm A9 50 ppmC1 50 ppm D2 −18 −24 −29 Example 7 50 ppm A2 50 ppm C1 50 ppm D2 −26 −29−28 Example 8 50 ppm A3 50 ppm C1 50 ppm D2 −30 −27 −30 Example 9 50 ppmA5 50 ppm C1 50 ppm D2 −22 −29 −30 Example 10 50 ppm A10 50 ppm C1 50ppm D2 −19 −30 −29 Example 11 50 ppm A6 50 ppm C1 50 ppm D2 −16 −26 −29Example 12 50 ppm A15 50 ppm C1 50 ppm D2 −28 −30 −31 Example 13 50 ppmA13 50 ppm C1 50 ppm D2 −14 −22 −28 Example 14 — 75 ppm C1 75 ppm D2 −12−17 −21 (comparative)

TABLE 4 CFPP effectiveness in test oil 2 The additive constituents Awere mixed with 5 parts of B2) and tested for their CFPP effectivenessin test oil 2. CFPP [0° C.] Constituent 300 A 100 ppm 200 ppm ppmExample 15 (comparative) A1 −11 −20 −21 Example 16 (comparative) A2 −11−22 −23 Example 17 (comparative) A3 −10 −20 −22 Example 18 (comparative)A4 −10 −18 −23 Example 19 (comparative)  A13 −8 −10 −17 Example 20(comparative) — −6 −8 −9

TABLE 5 CFPP and dispersancy action in test oil 3 For the dispersiontests in test oil 3, an additional 200 ppm of the additive B1) weremetered into all measurements. Test oil 3 (CP −6.7° C.) SedimentAppearance Additives [% by of oil A C vol.] phase CFPP [° C.] CP_(CC) [°C.] Example 21 (C) 100 ppm  50 ppm 0 turbid −23 −5.9 A1 C1 Example 22(C) 100 ppm  50 ppm 7 turbid −24 −3.3 A1 C2 Example 23 (C) 100 ppm  50ppm 10 turbid −21 −2.4 A2 C2 Example 24 (C) 100 ppm  50 ppm 20 cloudy−21 −0.8 A1 C3 Example 25 (C)  50 ppm 100 ppm 20 cloudy −26 −1.4 A2 C1Example 26 (C) 100 ppm  50 ppm 10 turbid −28 −1.4 A3 C1 Example 27 (C) 50 ppm 100 ppm 0 turbid −28 −5.3 A3 C1 Example 28 (C) 100 ppm 100 ppm 7turbid −21 −3.6 A4 C1 Example 29 (C)  50 ppm 100 ppm 13 turbid −27 −2.0A4 C1 Example 30 (C) 100 ppm  50 ppm 3 turbid −22 −6.1 A5 C1 Example 31(C)  50 ppm 100 ppm 15 turbid −22 −2.0 A5 C1 Example 32 (C) 100 ppm  50ppm 20 cloudy −23 −1.6 A6 C1 Example 33 (C)  50 ppm 100 ppm 3 turbid −21−4.4 A6 C1 Example 34 (C) 100 ppm  50 ppm 0 turbid −25 −6.2 A15 C1Example 35 100 ppm  50 ppm 16 clear −18 +3.0 A14 C1 Example 36 150 ppm —20 clear −20 +3.4 A1 Example 37 (C) 150 ppm — 20 clear −19 +3.2 A2Example 38 (C) — 150 ppm 10 cloudy −20 +0.1 C1 Example 39 (C) — — 25clear −19 +3.6

TABLE 6 CFPP and dispersancy action in test oil 4 For the dispersancytests in test oil 4, an additional 200 ppm of additive B1 were meteredinto all measurements. Test oil 4 (CP −8.2° C.) Additives SedimentAppearance CFPP CP_(CC) A C [% by vol.] of oil phase [° C.] [° C.]Example 40 (C) 100 ppm 100 ppm 0 turbid −24 −6.3 A1 C1 Example 41 (C)100 ppm 100 ppm 0 turbid −24 −7.5 A1 C1 Example 42 (C)  50 ppm A3 100ppm 0 turbid −24 −5.4 C1 Example 43 (C)  50 ppm A3 100 ppm 0 turbid −28−5.3 C1 Example 44 (C) 100 ppm  50 ppm  50 cloudy −23 −3.3 A5 C1 Example45 (C) 100 ppm 100 ppm 0 turbid −23 −5.5 A5 C1 Example 46 (C)  50 ppm A5100 ppm 70 cloudy −24 −4.3 C1 Example 47 (C) 100 ppm  50 ppm 16 clear−18 −1.1 A14 C1 Example 48 (C) 150 ppm — 20 clear −21 +2.4 A1 Example 49(C) — 150 ppm 35 cloudy −20 +1.2 C1 Example 50 (C) — — 20 clear −18 +2.6

TABLE 7 CFPP and dispersancy action in test oil 1 For all dispersancytests in test oil 1, an additional 75 ppm of additive B3 were meteredinto all measurements Test oil 1 (CP −9.0° C.) Additive SedimentAppearance of A C D [% by vol.] oil phase CFPP [° C.] CP_(CC) [° C.]Example 51  50 ppm A1 50 ppm C1  50 ppm D2 0 turbid −29 −7.2 Example 52 80 ppm A1 90 ppm C1  90 ppm D2 0 turbid −30 −8.0 Example 53  50 ppm A250 ppm C1  50 ppm D2 0 turbid −27 −7.4 Example 54  50 ppm A3 50 ppm C1 50 ppm D2 0 turbid −29 −6.7 Example 55  50 ppm A4 50 ppm C1  50 ppm D20.5 turbid −28 −6.0 Example 56  50 ppm A6 50 ppm C1  50 ppm D2 0.5turbid −28 −6.7 Example 57 (C) 100 ppm A1 50 ppm C1 — 0.3 turbid −24−6.7 Example 58 150 ppm A2 —  50 ppm D2 10 cloudy −24 −0.5 Example 59(C) — 50 ppm C1 100 ppm D2 2 turbid −25 −4.5 Example 60 (C) — — — 25clear −21 −2.2

1. An additive for middle distillates having a maximum sulfur content of0.05% by weight, comprising at least one fatty ester of an alkoxylatedpolyol having at least 3 OH groups (A) and at least one polarnitrogen-containing paraffin dispersant (D), said fatty ester having anOH number of less than 15 mg KOH/g.
 2. An additive as claimed in claim1, wherein the at least one fatty ester of an alkoxylated polyol (A) isderived from a polyol having three or more OH groups which has beenreacted with from 1 to 100 mol of alkylene oxide.
 3. An additive asclaimed in claim 1, wherein the at least one fatty ester of analkoxylated polyol (A) has been esterified with a fatty acid having from8 to 50 carbon atoms.
 4. An additive as claimed in claim 1, wherein theat least one fatty ester of an alkoxylated polyol (A) has beenesterified with a mixture of at least one fatty acid having from 8 to 50carbon atoms and at least one fat-soluble, polybasic carboxylic acid. 5.An additive as claimed in claim 1, wherein the at least one fatty esterof an alkoxylated polyol (A) is derived from glycerol.
 6. An additive asclaimed in claim 1, wherein the polar nitrogen-containing paraffindispersant present is a low molecular weight or polymeric, oil-solublenitrogen compound.
 7. An additive as claimed in claim 1, wherein thepolar nitrogen-containing paraffin dispersant is an amino salt amide ofsecondary fatty amines having from 8 to 36 carbon atoms or mixturesthereof.
 8. An additive as claimed in claim 1, further comprising atleast one ethylene copolymer (B).
 9. An additive as claimed in claim 8,wherein the ethylene copolymer (B) contains at least one unsaturatedvinyl ester of an aliphatic carboxylic acid having from 2 to 15 carbonatoms.
 10. An additive as claimed in claim 8, wherein the ethylenecopolymer (B) contains from 10 to 40 mol % of comonomers.
 11. Anadditive as claimed in claim 1, further comprising at least onealkylphenol-aldehyde resin (C).
 12. An additive as claimed in claim 11,wherein the alkyl radicals of the alkylphenol-aldehyde resin (C) havefrom 1 to 50 carbon atoms.
 13. An additive as claimed in claim 11,wherein the alkylphenol-aldehyde resin (C) is derived from at least onealdehyde having from 1 to 10 carbon atoms.
 14. A dispersion comprisingan additive as claimed in claim 1 and an organic solvent or dispersant,wherein the additive is present in an amount between 5 to 90% by weight.15. A middle distillate having a maximum sulfur content of 0.05% byweight, comprising an additive as claimed in claim
 1. 16. A method forimproving the cold flow properties and paraffin dispersancy in a middledistillate having a maximum sulfur content of 0.05% by weight comprisingthe step of adding an additive as claimed in claim 1 to the middledistillate.
 17. An additive as claimed as claimed in claim 1, whereinthe polar nitrogen-containing parraffin dispersant is obtained byreacting aliphatic or aromatic amines with aliphatic or aromatic mono,di, tri or tetracarboxylic acids or their anhydrides.